I use https://www.vertumotors.com/service-repairs/priority-service-plan/
They have a jaguar main franchise down the road from me. covers all servicing costs based on the schedule of the car, i.e. belts etc. Includes them picking up and bringing back the car, can add on MOT too. Important to note, they will do belts, but only if the schedule is showing time to change, so if they have never been done, they will do at the schedule suppose to be done.
Couple of points it does not cover anything not serviceable i.e. wear and tear, no water pumps etc covered.
Took my out fixed monthly cost for 4 years, the garage I use has been good, the video they provide with any issue has been good.
As its a franchise you can get cheaper elsewhere, I use as my XF is rare and trying to keep main dealer history to protect value in the future.
Also have comprehensive warranty with Inchcape for the stuff that does break, used a few times over the last 3 years.